But even something small can do the trick: Case in point, the satellite ExoplanetSat, which could easily fit in a backpack.

About 4" x 4" x 12", roughly the size of a loaf of bread, ExoplanetSat isn't only unusual for its size. Once it launches (which NASA originally scheduled for fall though the project may be delayed), it will also look for stars differently from Kepler, which monitors 150,000 stars at once. ExoplanetSat will look at one star at a time, detecting the faint dimming of a star that occurs when an otherwise invisible planet crosses in front of it.

ExoplanetSat is also different from other satellites in that it's not a product of NASA, but was born out of a class project at MIT led by astrophysicist Sara Seager, known for her research on what the atmospheres of planets orbiting distant stars might look like through telescopes on Earth.

The challenge for the student scientists and engineers was to figure out how to find planets using CubeSat, a literal cube (about four inches on each side) that was created at California Polytechnic State University in San Luis Obispo about a decade ago.

The MIT students put three together to form ExoplanetSat, which has all the elements of a telescope -- lenses, detectors, power supply and more -- plus packages together two elements that are separate on traditional telescopes: Space telescopes usually have a second small scope on the outside of the big telescope. It's used to spot the objects that the big scope should zoom in on. The ExoplanetSat, however, has both the star finder and the star gazer in one unit.

When in orbit, it will complement the work of Kepler, which searches for distant planets that are too far to check out for signs of life. ExoplanetSat, meanwhile, will search for Earth-like planets orbiting relatively close sun-like stars.